1. Field of the Invention
This invention relates to a circuit arrangement for converting an input voltage into a proportional output signal with the aid of a converting impedance, and to the use of this arrangement.
2. Discussion of the Background
Generic circuit arrangements are known which have fixed converting impedances are used for converting the input voltage into a current which has a proportional or otherwise clearly functional relationship to this voltage. The current, if necessary, is converted by suitable means, for example an amplifier having a fixed gain, into an output signal which is proportional to the input voltage (see for example U. Tietze, Ch. Schenk: Halbleiterschaltungstechnik (semiconductor circuit engineering), 5th edition, pages 106-108).
However, these circuits, which are well known to the specialist, are unsuitable, or suitable only when very expensive components are used, if requirements are set simultaneously which include high precision and long-term stability in the conversion of the input voltage and, in addition, necessitate the converting impedance to have extreme values.
Such requirements occur, for example, in processing the output signal of a voltage transducer constructed as a capacitive voltage divider where, because of the restriction in time constant required by the standard, it is necessary to use a converting resistance of very high value as a converting impedance. In addition, this impedance must have high electric strength because of the occurrence of transient over-voltages.
It is not possible to implement conventional circuits meeting such requirements, at least not by cost-effective means.